Method and apparatus for testing materials



Nov. 4 1924:.7

R.B.SMWH

METHOD AND APPARATUS FOR TESTING MATERALS Filed Dec. 5 1921 mi v.

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INVENTR Mw/5j; A ATTORNEY Patented Nov.. Li, 192% METHOD .AND APPARATUS FOR TESTTNG'MATERIALS.

Application filed December 5, 1921. Serial No. 519,921.

To all whom t may concern;

Be it known that I, ROBERT BIGHAM SMITH, a citizen of the United States, and resident of Macon, in the county of Bibb and State of Georgia, have invented certain new and useful Improvements in Methods and Apparatus for Testing Materials, of which the following is a specification. Y

The invention relates to a method and apparatus for testing materials when mounted in a stretching machiiieand specifically relates to an improved means for centering and aligning fabrics when mounted in sucli machines.

It is the usual practice in testing fabrics to determine their strength and elasticity to cut strips in botli the warp direction and in the filling direction to fray the longitudinal edges to leave the requisite width of unfrayed strip and to then mount the strip in some suitable form of testing machine. One such machine now in general use is identified as a jaw pull tester of the inclination balance type and which includesy a pair of work clamping jaws constructed to engage opposite ends of the longitudinal strips. As at present practiced the same strip will give different data under sucfor presetting theL direction and center ofy draft to which the fabric is to be subjected. This is attained simply by marking on the strip before it is set up in the machine, a long sight or identification line. This line can, of course, be accurately positioned to extend parallel to the threads and thus insure a true testing of the strength of the fabric in the direction of the threads under test. j

Another object of the invention and particularly featuring tlie mechanical phase of the disclosure, is to provide a simple means for insuring the mounting of the fabric ing :it inl a conditioning oven before it is mounted in the testing machine. It is necessary that thev dried strip be *quickly` positioned in the testing machine before the strip can acquire moisture from the air and thus introduce'an error into the desired readings.

Accordingly, .another object of the invention is to provide a simple form of in# dicating means Vfor assisting the operator in effecting a lquick mounting and in determine ing the proper position of the sample' inthe testing machine.

Still another object of the invention is to provide a simple form of centering and aligning means which can be marketed as an attachment for .installation in testing machines of the type under consideration to Y' assist in locating the work in suchy machines.

Various other objectsy and advantages of the invention will be in part obviousr from an inspection of` the accompanying drawings and in part Lwill be more fully set forth in the following particular description of one form ofmechanism embodying my invention, and the invention also consists in certain new and novel features of construction and combination of parts here# equipped with a preferred embodiment of y my invention;

Figure 2 is a plan view looking down upon the device shown in Figure 1;

Figurel 3 is a/detailed transverse sectional view 'takeny on the line 8-3 of Figure 2 `looking in the direction indicated by the arrows; and

Figure 4 is a plan view partially in dotted outline of a strip of fabric to be tested. Tny the following description and in the fil claims7 partswill be identilied byspecific names tor. convenience of expression but they are intended to be as generic in their application to similar parts as the art will permit. y

In the drawings there is .shown part of a conventional form of testing machine and which includes a track 10 upon which is mounted a pair of jaw carriages 11 and 12,

carryingarespectively workA clamping jaws` 13 andlt'andwhich j aws'arexdesigned to be moved relativeto each other yso as `to stretch andirupture the work W clamped tlierebetweemaall as is lwell known inf operationv ot testing machines otzthe inclination balanced type.

-Reterringfto thefmethod feature ot this disclesurelitfzis to be understood that-the stripgVf, w-hich kin this case isa square woven autoniobileitire tabrlc, includes longitudinal threads Z andxtransverse threads if, with the longitudinal threads frayed routzas shown in testing;v the strip; either bythe machine here-v in disclosed-For by any-other method, care is exercised thatl the. loci: ot the Aline of strain on thewstrip Ibei-apportioned sym.-y

inetrically on opposite sides ot the line a so.

as to insure-'atrue test inthe direction oic the presetwline..

lnrorder to insure the ycoincidence ot the niarkedfline on the 4material under test with the-center`ofithe line o-tipull when the ina-vr erialfisrfmounted inxa testing fmachinev recoursey isf-had to an indicating orcentering de vice'otthe typellierein disclosed. z

Referringftofthespecitic torni; of the in-1 vention disclosedin the drawings the indiyeating devicewisrsliown ito be in the i'oriny oit' an attachment.` `15 demountably secured to some suitable part ot they machine vor other convenient support. In the torni ot the inachine illustrated rthe flange 16 ot a boss 17 Jforming part ot one of the carriages 12 with its 4securingibolts 18 provides a convenientv means for securing the attachment in place.

lheffattachment includes l a 'long flat arm 19 which*'constitutesa support extending parallel toxthefline otfniovement of the` jaws and lapping the same as particularly shownl in Figure 21 A1 pair.` ot glass supporting trauies-QO-faiid. 21: are slidably mounted on the. arm 19 and-.are adjustably 'fastened v thereto by means of bolts 22 passing through ythus provides means tor adjusting the plates as a whole transversely ot the line of movement ot the jaws. These plates are each 1provided with a spring keeper 2G, so arrangedV that a plate of transparent material 27, such as glass', may be mounted `therein in position to extend lengthwise ot theline of movement and between the aws. The glass is demountably `held in positionk on'the two plates 2t by means ot trie` spring keepersso that the glass plate can be readily removed and a different sized plate substituted there for in testing the different materials.- The glassplate is provided with a yhair linev 28 preferably etched on ythe under side -thereotl as is usual in marking hair lines on glass. The plate isso set that the hair line will be set accurately relative to the jaws and in such a way that it will extendaccurately in a direction parallel to vthe line of movement between the aws-and will connect the center ot the line of pullA ot' one jaw with tie corresponding center oit the other jaw. Preferably the plate is disposed so as to be relatively closevto the work `W as shown ink Figure 1 and thus minimizeany errors due to pznallazrreadii'ig` between the line CSand the line ,a on tliework.

It is obviously within the scope. otthe disclosure to substitute anyother indicating line for the marking fon the. glass disclosed, and one such equivalent structure is a tine.- wire or hair stretched between the'trames 2O and 21 iny place ot the'glass disclosed in the preferred embodiment orp vthe invention herein illustrated. f y

lnl operation,l and with i the f attachment vmounted insplace and with the proper size glass in'fposition, the` trames carrying the glass will ber accurately and cautiously adjusted to bringthe indicatingrline in centered-position between lthe jaws. l/l/Tith the jaws in openzposition to receivethe work which has been previouslyVv marked witlrthe. linea as liereinbetore suggested, it is withdrawn from the conditioning oven7 if it is so pretreated7 and is quickly clamped in position between the jaws. The necessity for transverse movement otithe strip is readily determined simply by 'havingthe lines coincide and the presetpoeition ot thejaws determine the longitudinal distance between the jaws at the start ot the testing-operation. rThe aws are then screwed into work clamping position engaging the located stripand the machine is setin operation to testithel fabric `as is well known'in the operationot` suoli machines. l Y

By tollowingthe method and usingthel machine herein disclosed it is possible to accurately locate the line of pull on the fabric at right angles to the aws of the testing machine and to center' the fabric'inthe jaws. ln this way the strain on each side of the center of stress is equal or approximately equal and in this way friction on the moving parts of the testing machine is reduced to a minimum and in this way the two strips of the material to be tested is ascertained without the introduction of errors due to friction on parts of the machine not intended to compensate for any such friction.

By means of the machine disclosed it is possible to obtain reading oitl strength and elasticity from different strips oi' the same material and which reading` will be relatively close to each other thus indicating that successive tests are made under practically identical conditions.

Strains on the fabric have been symmetrically disposed on opposite sides of the longitudinal medial line of the strip and in general an improved actuation of the machine has been attained.

While l have shown and described, and have pointed out in the annexed claims, certain novel features of my invention, it will be understood that various omissions, substitutions and changes in the form and details ot the device illustrated and in itsoperation may be made by those skilled in the art without departing from the spirit ot the invention;

Havingk thus described my invention, l claim:

l. ln a device ot the class described, the combination with a testing machine including a pair of work engaging jaws movable relative to each other in one direction to stretch the work carried therebetween, a transparent plate adapted to be positioned above the portion of the work held between the jaws a support for said plate, said plate provided with an indicating line thereon extending in said direction and connecting the centers of the points of engagement between each jaw and the work engaged thereby.

2. ln a device of the class described, the combination with a testing machine including a pair of work engaging jaws movable relative to each other in one direction, to

4relative to each other in one direction to stretch the work carried therebetween, a transparent plate adapted to be positioned above the portion of the work held' between the jaws, said plate provided with an indicating line thereon extending in said direc-- tion and connecting the centers of the points of engagement between each jaw and the work engaged thereby, and means for securing the plate in adjusted position.

4. In a device of the class described, the combination with a testing machine including a pair of jaws for clamping opposite ends of a piece of work to be tested, of aligning means disposed kbetween the jaws, in position to be adjacent tothe work to be tested and extending parallel to said direction of movement of the jaws.

5. A testing machine including a pair ot work engaging jaws movable relative to each other to stretch the work therebetween, and indicating means adapted to be disposed between the jaws and relatively close to the work to avoid parallax in determining the proper position of the work in mounting the same in the machine.

6. An attachment for a stretching machine including a support, means for securing the support to the machine in position to extend parallel tothe line of stretch in the machine and means providing an indicating line carried by said support and extending lengthwise of the support.

7. An attachment for a testing machine including a support, means for securing the support to the machine, a plate frame adjustably mounted on said support, a transparent plate demountably positioned in said rame, said plate provided with an indicating line adapted to coact with a similar line on the material to be tested.

Signed at Macon, in the county of Bibb and State of Georgia, this 28th day of November, A. D. 1921.

ROBERT BIGHAM SMITH. 

